I have my first, second, and third items and then I want the forth item to go to the next line no matter how wide is the space.
.box { display: flex; flex-flow: row wrap; justify-content: space-around; align-items: flex-start;}.it { max-width: 420px;}<div class="box"><div class="it">1</div><div class="it">2</div><div class="it">3</div><div class="it">4</div></div>